The police department retired the Star of officer Clifton Lewis. He was killed nearly one year ago while working an off-duty security job.

Lewis was known in the neighborhood as "6-9." While he wasn't quite that tall, Clifton Lewis was a big guy, so "6-9" worked as a nickname. When he was murdered inside a West Side convenient store last year -- four days after Christmas -- word spread fast through the neighborhood.

"Nobody knew who Officer Lewis was, but as soon as you said '6-9,' people started crying and remembering," said Chicago Police Dep. Supt. Al Wysinger.

There were tears of remembrance Monday as Officer Cliff Lewis's family placed his star, Number 4103, in the police department's Honored Star case.

An emotional superintendent Monday remembered when he went to offer Lewis's family some comfort after the shooting and found his mom to be incredibly strong.

"I realize it was faith holding her up, faith that allowed perseverance in the absence of understanding, faith so obviously instilled in Cliff that it evoked great accomplishment in his career even in the face of high pressure situations," McCarthy said.

Lewis was off-duty working security when two men in masks burst in in a robbery attempt. One with a machine pistol started firing. Lewis was hit four times.

While two men have been charged, two others -- including, it's believed, one of the shooters -- remain at large.

Earlier this month, inside an apartment on the West Side, police recovered a semi-automatic handgun that was owned by Officer Lewis and was apparently being held by a teenager since arrested for unlawful possession.

"We're gonna continue to follow the evidence where it leads," said Cook County State's Attorney Anita Alvarez.

Prosecutors and police are guarded about where they are in the investigation, apart from a pledge.

"I want to close with a promise that we will bring all of those accountable for Cliff's murder to justice," McCarthy said.

It is not yet clear is what led police earlier this month to the apartment in the Austin neighborhood where they recovered the handgun registered to Officer Lewis. It was being kept in a cooler, allegedly, by a 19-year-old alleged gang member who is now charged with unlawful use of a weapon by a felon and possession of a stolen firearm. How, and to what extent, that fits into the investigation is something police are not now prepared to discuss.